With the development of technology and the continuous growth of population in today's world, the demand for energy is certainly getting higher. In addition, with the heavy consumption of non-renewable energy, the cost for energy is getting higher as well. Therefore, in order to achieve energy saving and reduce energy cost, many countries have started to more strictly limit the usage of energy in many aspects. To reduce energy usage in factories, many laws and policies are established to encourage all the companies to increase their efficiency on production. As for motors which are usually responsible for more than 70% of total energy usage in factories, manufacturers are also trying to achieve better efficiency on them. Considering the many types of motor structures, the most common one is the induction motor. Furthermore, permanent-magnet motor and reluctance motor are also popular because of their simple structures, easiness to repair, and high efficiency.
For induction motors, the primary way of enhancing the efficiency is to reduce the internal energy loss. The internal energy loss can be divided into five categories, including iron loss, rotor and stator's resistance loss, air loss, friction loss, and stray loss. To reduce the rotor and stator's resistance loss, one of the main focuses of development is to use copper as the material for the rotor. For permanent-magnet motor, the magnet plays a big role in the motor's performance. Especially with the development seeking high efficiency, portability, and high torque density nowadays, the development not only focuses on increasing the magnetic energy product of the magnet, but also tries to reduce magnetic loss and effectively guide the magnetic circuit. In the designs of mover and stator in traditional machines, due to the limitation of the shape of the magnet and the stamping process of the silicon-steel sheet, the surface magnetic field is usually higher at the edges of the magnet. Furthermore, normal structures of mover and stator are made of silicon-steel sheet and rare earth magnet (for example: Dysprosium). The cost of rare earth material and manufacturing module for manufacturing permanent-magnet is relatively high, so the total cost of the entire manufacturing process becomes even higher.
Therefore, there is a need for a mover and stator assembly of electric machine that can increase the efficiency, reduce energy loss, and reduce the manufacturing cost.